The effects of age and exercise intensity of physical conditioning on claudication pain symptoms and leg circulation of patients with intermittent claudication will be examined. It is hypothesized that (1) older patients (greater than 70 years of age) will have greater disease severity, and greater relative improvements in claudication pain and leg circulation following 4 months of exercise rehabilitation than younger patients (greater than 60 years of age), and (2) the improvements of both age groups will be greater following a rehabilitation program that uses higher exercise intensity (70% of walking capacity) that a program that uses lower intensity (40% of walking capacity)> The clinical significance of these anticipated findings is the exercise rehabilitation becomes more effective in the treatment of claudication pain as patients age, and a program should consist of exercise at higher rather than lower intensity for greater improvements in claudication pain and leg circulation, which may circumvent disease progression to more serious endpoints.